The Clinical Radiation Research Center (CRRC) programs constitute the major investigative activities of the Division of Radiation Oncology of the University of Rochester Cancer Center (URCC). The unique aspect of the CRRC and the URCC is the integration of research in the clinical sphere and the laboratory setting. The Radiation Oncology Clinical Investigative Program of the CRRC utilizes the laboratory to model and simulate clinical problems to better understand the pathophysiologic effects of irradiation in humans with malignant disease. The Radiobiology and Biophysics Program investigates methods for combining radiation and other modalities for effective cell killing by the use of tumor models in vitro and in vivo. When promising results are found in the laboratory, pilot protocols are written and implemented in the University of Rochester Medical Center through the collaboration of the divisions of Radiation and Medical Oncology. The Radiation Physics Program provides special support for the other programs and conducts its own research in treatment planning, developing clinical guidelines, mathematical optimization, and applying CT scanning imagery. Personnel and programs interact at different levels and combine efforts in various theme projects such as combined modality treatment of brain tumors, radiosensitizers, and bone marrow regeneration.